Cable television is becoming more popular and millions of homes use and receive analog cable signals from a cable supplier to watch favorite programs and in some instances receive other information. Typically, each subscriber has a Set-Top Box, (also referred to as a Home Terminal) that rests on the standard television and receives from the cable headend down-stream transmissions such television shows. The cable headend typically has a connection to a national programming supplier such as a television network.
Advances in communication are now making possible the use of digital video or EPPV/VOD products that allow cable suppliers to offer enhanced pay-per-view (EPPV) and video-on-demand (VOD) services while having a digital network solution. By using a digital network, the use of out-of-band signaling capabilities are now possible as well as video and audio transmission in both the uplink and downlink direction. It is now possible to have a digital video Set-Top Box or Digital Video Home Terminal that can receive downstream transmissions and transmit upstream signals as necessary.
With the use of a digital network and RF Trunk, it is possible for hundreds of Digital Video Home Terminals to reside on one RF Trunk. With the use of hundreds of Digital Video Home Terminals that can generate a message upstream to the cable headend, it is possible for message collisions to occur when two or more Digital Video Home Terminals send a message about the same time, requesting video programming or other information and services. It is therefore necessary to design a system using Digital Video Home Terminals that avoids collisions with messages generated from various Digital Video Home Terminals located at different subscriber premises. Additionally, any solution to this problem should require little processing power and memory within the Digital Video Home Terminal or Set-Top Box to reduce the cost, size and complexity of Set-Top Box. To reduce the overall cost of the system to the subscriber, it is desirable that any major processing to avoid message collision be accomplished at the cable headend.